<!DOCTYPE html>
<html>
<head lang="en">
  <meta charset="UTF-8">
  <title></title>
  <style>
    .box{
      width: 300px;
      height: 300px;
      border: 1px solid red;
      margin:100px auto;
      background-color: orangered;

      transition:transform 1s;
    }
    /*
      deg 角度
      rotate(角度)
      正值 顺时针  负值逆时针
    */
    div:hover{
      transform:rotate(-45deg);
    }
  </style>
</head>
<body>
    <div class="box">
      桃花潭水深千尺，疑是银河落九天
    </div>
</body>
</html>